Molecular Dynamics of Hydration Shells of Adsorbates in Entropy-Driven Adsorption (Hydrophobic Bonding) to Activated Carbon Surfaces.

Hydrophobic bonding is a phenomenon wherein the adsorption of solutes from aqueous solutions is driven largely by the desire of solvent molecules to interact with each other, thus squeezing out solute molecules onto the adsorbent surface. A novel computational analysis of hydration shell water dynamics was used to study the driving force for the hydrophobic bonding of five small drug molecules to activated carbon. It was demonstrated that the solvation of these drug molecules produced hydration shells of lower density and molecular mobility than bulk water, up to 10.

Disagreements Between Calorimetric and Van't Hoff Enthalpies of Adsorption II: Effect of pH and pH Buffers on Phenobarbital Adsorption to Activated Carbon.

The reported inconsistencies between the van't Hoff equation and calorimetry hinder the utility of thermodynamics in biochemical and pharmaceutical research. A novel thermodynamic approach is developed herein for ligand adsorption with a focus on the interpretation of calorimetric data in the presence of concurrent proton exchange reactions. Such exchange reactions typically result in a pH-dependence of calorimetric measurements that obscures intrinsic binding enthalpies.

Disagreements Between Calorimetric and Van't Hoff Enthalpies of Adsorption: A New Langmuir-like Model to Account for the Effect of Solvent Displacement Stoichiometry.

The reported inconsistencies between calorimetry and the van't Hoff equation hinder the utility of thermodynamics in pharmaceutical research. In ligand binding or adsorption assays, it is believed that the van't Hoff equation falls short because of the lack of stoichiometric treatment in the equilibrium constant. A new modified Langmuir-Like equation that accounts for the stoichiometry of solute adsorption and solvent displacement is proposed in this work.